NED Abstract

Copyright by American Astronomical Society.
Reproduced by permission
2012ApJ...746L..22K
Understanding Dual Active Galactic Nucleus Activation in the nearby
Universe
Koss, Michael; Mushotzky, Richard; Treister, Ezequiel; Veilleux, Sylvain;
Vasudevan, Ranjan; Trippe, Margaret
Abstract. We study the fraction of dual active galactic nuclei (AGNs) in a
sample of 167 nearby (z < 0.05), moderate-luminosity, ultra-hard
X-ray-selected AGNs from the all-sky Swift Burst Alert Telescope (BAT)
survey. Combining new Chandra and Gemini observations together with
optical and X-ray observations, we find that the dual AGN frequency at
scales <100 kpc is ~10% (16/167). Of the 16 dual AGNs, only 3 (19%) were
detected using X-ray spectroscopy and were not detected using emission
line diagnostics. Close dual AGNs (<30 kpc) tend to be more common among
the most X-ray luminous systems. In dual AGNs, the X-ray luminosity of
both AGNs increases strongly with decreasing galaxy separation, suggesting
that the merging event is key in powering both AGNs. Fifty percent of the
AGNs with a very close companion (<15 kpc) are dual AGNs. We also find
that dual AGNs are more likely to occur in major mergers and tend to avoid
absorption line galaxies with elliptical morphologies. Finally, we find
that SDSS Seyferts are much less likely than BAT AGNs (0.25% versus 7.8%)
to be found in dual AGNs at scales <30 kpc because of a smaller number of
companion galaxies, fiber collision limits, a tendency for AGNs at small
separations to be detected only in X-rays, and a higher fraction of dual
AGN companions with increasing AGN luminosity.
Key words: galaxies: active, galaxies: interactions, X-rays: galaxies